#include<stdio.h>
#include<math.h>
void main()
{
    float a,b,c,p,area;
    printf("please input the lenth:");
    scanf("%f %f %f",&a,&b,&c);
    p = (a+b+c)/2;
    area = sqrt(p*(p-a)*(p-b)*(p-c));
    printf("a = %5.2f,b = %5.2f,c = %5.2f\n",a,b,c);
    printf("area = %7.2f\n",area);

}